One of the primary impediments to high speed from an underwater vehicle is turbulent flow of the ambient water immediately adjacent to the exterior surface of the vehicle. The U.S. Navy has experimented with many methods of maintaining a laminar flow so as to enable high speeds of these vehicles, particularly torpedoes. One such method which has involved considerable experimentation has been boundary layer control by suction (BLCS). Even though the possibility of maintaining laminar flow over smooth surfaces by suction was first proposed by Prandtl in 1904, it was not until the late '50's that the Navy gave serious consideration to applying this technique to torpedo design. In 1962, the Naval Ordnance Test Station maintained full length laminar flow over a porous shell wind tunnel model at Reynolds numbers up to 12.times.10.sup.6 and angles of attack up to 4 degrees. In 1963, Northrup achieved a laminar flow over a slotted shell wind tunnel model at Reynolds numbers up to 60.times.10.sup.6, and the following year achieved laminar flow over a slotted shell water tunnel model at Reynolds numbers up to 20.times.10.sup.6.
Previous application of boundary layer control suction to porous-shelled torpedoes included simply a single suction compartment between the hull of the vehicle and the outer porous shell. This approach is not efficient for the typical torpedo shape with a blunt nose since the turbulent flow is much less of a problem at the mid section of the torpedo as compared to the nose and tail sections thereof. Consequently, the prior art approach, which is acceptable for an ellipsoidal-like shape, would result in a waste of power for a cigar-like shape if suction was applied equally along the full length of the torpedo.